Recent concern over the the environmental effects of industrial and automotive emissions has resulted in increased effort to develop catalysts which are effective in the oxidation or reduction of undesirable waste gases to innocuous products. In addition to the fundamental need for good catalytic activity for the desired conversions, catalysts have been sought which retain this catalytic activity over extended periods of time in environments which are normally detrimental to the catalytic effect of many metals such as platinum. Most platinum catalysts, for example, are markedly depreciated in their catalytic activity in the presence of combustion residues from standard antiknock gasoline additives. Moreover, many industrial processes, such as those found in petroleum refining, provide high temperatures or reducing conditions detrimental to most known catalysts.